Protective device for dynamo-electric machines



June 7,1927. 1,631,726

H. C. HASTINGS ET AL PROTECTIVE DEVICE FOR DYNAMO ELECTRIC MACHINES Filed Nov. 13, 1923 Invennor-s: Hammond C-Hasnings;

C' r-il J-Sarjeanb;

Their Abner-nes- Patented June 7, 1927. i I i UNITED STATES PATENT OFFICE.

HAMMON'D CHARLES HASTINGS AND CYRIL JOHN SARJEANT, OF RUGBY, ENGLAND; ASSIGNORS TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

PROTECTIVE DEVICE FOR DYNAMO-ELECTRIC MACHINES. Application filed November 18, 1923, Serial No. 674,584, and in Great Britain December 14, 1922.

This invention. relates to protective despring 13. Before the contacts 7 and 8 of 50 vices for dynamo electric machines and the main breakcr engage, the pole piece vmore particularly ,to gmeans .for automatiof the circuit breaker is brought in contact cally changing the calibration of the cirwith the poles of magnet 2. As the arm 6 5 cuit breaker ofa'feeder where one or more moves it first closes an auxiliary contact machines are required to. run in parallel and then opens the contact 43 through link 65 andsupply current, through the 'circuit mechanism 14 pivoted at 44. The auxiliary breaker. Such, an arrangement is particucontact 15 short circuits the coil 16 and the larly applicable to. automatic sub-stations resistance 22 thereby connecting. the hold- 1 :where--there ;are ynoattendants. present to ing coil 3 of the main breaker across the alter? the calibration of the circuit .breaker full voltage of the cont ol b ba Th so .when: one or more of the machinesis autoshort circuiting of coil 16 causes the contact matically. cut.;out, .or cut into circuit, al ,17 to open, and thus deenergize the closing thoughtheinventionjs.not limited in its coil 11 of the main breaker, thus allowing l5 p h ati t an automatic sub-station; thc'lever 9 to assume its normal "position The. .-accompanying, diagram illustrates andpermitting the strain set upin spring one method ofcarry1ng. outv our invention, -13 to operate contact arm 6 to bring conas applied to a. high speed circuit breaker, tact 7 in engagement with contact 8. .:such;:for': example; as. is; described in the pat- Bridging contact43 when operated through .ent of John.F. TritleyNo. 1,560,440, dated the link mechanism 14'opens the circuitof --November-3, 1925. the-coil 39 of the contactorAl thus allow- .5 Imthefdrawing, a c ircui t breaker 1 is ingthc contact 40 toopeni When this con adapted to be jconnected to afeeder 37.: In. tact opens it removes the short circuit from worder to close thisbreaker, push. button the resistance and} the main circuit .?21 =is closed-and completes thecircuit er an breaker is then held tri its closed position energizing ;coil. 18 vfor,acontactor 38;: This by the holding 'cOili3' which is connected .c-loses contact-s laand 20,,theformer comin series with ther'esistance 22.

. i letingacircuiaaround the push button, so The object of. first short, ci'rcuiting the that omits beingreleasedthe contactoi' 3S resistance 22 and then removing'the short 30 ;will',remainj .cIosed..;1C ontact 20 completes circuit'is to obtain bet-tercalibration of the "the circuitv ofai-coil 16 of a contactor 42 "circuit breaker if the magnetizing-current 30 through aholding coils? of .the circuit. is first raised above normal andlthen'debreaker 1,1 and a eontact 40'of a cont-actor creased to the normal. This feature is :41.- The coil. :16 is in parallel with resistance claimed in an application'of John F. Tritle,

35 v22.. .The contact 10..remains closed as long and Jacob XV. McNa-iry, Serial N0. 6,204,

as the circuit breaker 1 is open, asits operfiled February 2,1925, a division of a former s5 at-ing coilh39nis energized throughbridging application, Serial No. 683,533, filed Decem- .'contactildwhich relua insclosedso; lon as her 31, 1923, which said] applications are the mainbreaker 1 isjnits open position. assigned 'to the 'sameassigii'e'e as the present 4 Although-coil 3 is. thus energized, the application The calibration of the main efiect ofthe magnet2is notsufficient to close breaker with all the resistance-22 in circuit the main; circuit breaker.- is the lowest calibration required, when only ,Whenthe coil 16 of contactor 42 is enerone of the generators'35 or 36 is connected ized it causes the contact 1'1 to'closethere v to the bus bar 30 from which the feeder 37 45 by energizing'theclosingjcoil 11 of the is supplied, and these .machines are con- .breaker 1. The magnetic core 12 of this nected to the bus bar through circuit'intercoil 11 then attracts a lever 9v.pivoted at 45 rupters 31 and 33 respectively. When both which moves -the contact arm 6 toward the machines 35 and 36 are connected to the bus closed position 'against the action of the bar, it is necessary to raise the calibration of the breaker 1 in order to allow thev c rrent of both machines to pass through this breaker. (in-nit intcrl'uptcrs 31 and 33 are provided with auxiliary contacts 32 and 354 connected in series. and when both these intcrrupters are closed a circuit for coil 21, of coutactor ltl'is completed through a" bridglug contact 29 carried by a contacl'or l7. Contactor l6 tl'ieret'ore closes. and its contact' 26 short circuits resistance 22 to raise the magnetizingcurrent in the operating coil 3 of the hilt-"alter l to its maximum value. An auxiliary contact 24 on the contactor 46 closes thecircuit of the operating coil 25" of the contactor 47 through auxiliary contacts 32 and ill on the interrupters. The conlactor 47 then closes andits'contact 27. com'p letes a circuit across a portion of the resistance At the same. time an auxiliary contact 28' carried h'y this contactor. completes a circuit around the contact 24 on-contactor 4Gto form a. retaining circuit for the'coil'25and thc auxiliary con tact29 opens the circuit oi coil 23.

i'lh'e deeriergifzing of this c'oil opens contacts 2G..a'nd 24 andlthereby prevents 'c0ntactor 47 from being rec'los'ed if opened for any cause, until the con't'a'ctor' 6 has been asain c lo'sedl' The opening of contactor' 26 a oremoyes' the short circuit across the resistance 221 I U V Thelamo untofresistance short circu'ited by the contact 27 sufficient to raise' the calibration of the cireuifib'reaker to the correct setting for both machines 35 and 36 to supply power through the breaker,

While both mac'liin es'are running, it it is necessary to disconnect one of them front thefe ederfor any reason, its interrupter Willi he opened and the auxiliary contact carriedj' by the. interrupter will break .the circuit of coil 25 of tlielcontactor 47. When this coil is deenergiaedcontacts' 27,28 and 2t) assume their normal positions, the contact 27 r'emov- ;ing the short circuit across the section of 1;es istanc e 22 so that. themain lirealcerwill be cal ibrated t'o t-ake the load'of the machinewhich. is left runnin Auxiliary contact 28 when.=open ed. breaksthe circuit of coil 25 so. that it is impossible to reclose cont-actor 47 before contactor 46li as been closed. I

The auxiliary contact 29- on contactor l7 completes a. circuit for-th ecoil 23 so that when the machines are again to he run in parallel, this coil \yill a gain bcenergized'and the calibrationof the main breaker will be raised.

It is to be understood that the abore description isonly given by Way of example,

circuit :breaker.

and that other means may be employed for changing thecalibration of the main feeder It shouldlalso be understood that although a we hayedescribed a particular type of circuit breaker, the principle of our invention may he applied to other types of circuit breakers. and that. although we have only illustrated two machines, the invention is not limited t this nnmlacr as grculcr numl)(l' may he cmploycd.

\Vhat we claim as new and desire to secure hydiettcrs Patent of'thc'Unitcd'fitates, is,

l. The combination with an automatic circuit breaker arranged to interrupt a controlled circuit-in response to a predetermined value o'l'cnrrent, of a. calibrating dcyiceior rarying the value of current at which the circuit. hr'e'akcr"automatically interrupts the controlled circuit, a plurality of dynamo electric machines a'rraiige'd' to be; connected in the circuit through the said circuit breaker, and means autmnatically operated in response to the number of said machines iiicliided in the said circuit .for'varyiug the said calibrating'dei'ice.

2. The"combinatioriwith al'iau t matic 'ciis cnit' .ln'eaker' of the type: 'haX-"i'ng'a magnet for holding' the breaker closed against" the action of means responsiue toi the'current in; the controlled ci'rcuit tending to render the hol din" magnet in'efi'ective, of meansfo'r varying the cner gi'zationof the said holding magnet, a'pl'urali'ty of d namo electric machines arranged to be connected in the circuit throu h the. said breaker," and. means automatically operated in response to the number of said machine's includedin the said circuit" for controlling thesaid varying means.

31" The combination'with'an automatic circ'uitbreaker of the type havinga magnet for holding the breaker closed against'the action ofmeansresponsive" to the current in the, conti'olle'd 'circui'fit'ending to render the lloldingnie ans ineffective, ofavariable resistor for-'controll'ing-tl'ie energization of the said holding magnet, a 'plurality' of dynamo etectricmachines arranged to be connected inthe' circuit through the said breaker,- and means automatically operated responsively to varying the number ofsaid machines inchided in the said circuit for temporarily shortcircuiting the saitl resistor and' then regulating the effective resistance thereof to calibratethe breaker for the-"change in the number of machines included in the said circuit;

4. An electrical system comprising-a main circuit," interrupting" mean stherefor, a plurality (it secondary circuits, connecting means bctu-eemeach secondary circuit and thti'main' circuit and means responsive to the number of 1 connecting" means of the seeondary'c'ircuitsin a predetermined conditioli for controlling the=0peration of the in terrupting means of the main circuit.

51 The'combinati'onwith a main circuit, interrupting means therefor, aplurality of secondary circuits, a'cir'cuit interrupter between each secondary circuit and the main circuit, and means for opening the interrupting means of the main circuit in response to a current traversal thereof in excess of a predetermined value, of means responsive to the number of closed circuit interrupter-s of the secondary circuits for determiningg the value of the current traversing the main circuit that shall cause the interru iiting means of the main circuit to be opened.

In witness whereof, we have hereunto set our hands this twenty-ninth day of October, 1923.

HAMMOND CHARLES HASTINGS. CYRIL JOHN SARJEANT. 

